president's address — SECTION c. 79 



(Smith, 1908). The so-called syenite of Mackay's Bluff, near 

 Kelson, is sometimes placed among this general group of intrusions. 

 Further south, there are the ultrabasic rocks west of Lake Waka- 

 tipu, that have been already mentioned, and some sill-like serpen- 

 tine masses, and dykes of monchiquite in the Otago schists. Some 

 authorities class in this general group of post-Hokonui in'ru i ns, 

 the whole series of gneissic dicrites, noritei, and peridctites of the 

 Fiord region, the Longwood Range, Orepuki, and the Bluff, to- 

 gether with the more massive granites of Preservation Inlet and 

 Stswart Island. Gabbroid rocks, prcbably invading Mesozoic 

 sedimemts, occur in North Cant-rbury, and, perhaps, the plutonic 

 and dyke-rocks of Mount Tapuasnuka in the Kaikoura Mountains 

 may belong to this group, though Thomson (1918) is inclined to 

 connect them with the Middle Cretaceous volcanic rocks. 



The " Notocene" Rocks. 



The series of formations deposited after the Hokonui (Lower 

 Cretac90^s) orogeny commences with Middle Cretaceous (Alb'an) 

 beds, and extends up into the Upper Fliccane deposits. They have 

 always attracted much attention from New Zealand geologists, and 

 considerable diversity of opinion here has existed concerning them. 

 During the past decade nv;merous papers have appeared, and 

 though diversity of opinion still exists, a great advance has been 

 made in our knowledge. Of especial value has been thei detailed 

 palaeontological work of Bartrum, Chapman, Marshall, Suter, 

 Thomson, woods, and others. In general, there has been no doubt 

 as to the relative ages of the beds iij any one region, or the recog- 

 nitiom of differencei in age in the basal beds in different regions, but 

 the correlition of the succe ding formations in adjacent regions, 

 and the interpretation of the structural relationships of the several 

 beds to one another, arei matters that are still discussed. There 

 have been several hypotheses as to' the sequence of events forming 

 this great series of d'^oosits. The s mnlest among current v'ews 

 is that advocated by Marshall (1910, 1915). This considers that 

 the whole series of Cretaceous and Tertiary rocks is conformable 

 throughoiut. Overlap on to an evenly subsiding but irregular sur- 

 face accounts for the difference of age of the basal beds in different 

 regions. The period of greatest submergence was the period 

 when the limestone was deposited, so that the limestones in all 

 regions are coeval. They are succeeded by beds of a more elastic 

 character, indicating: the return of shallow-water conditions. To 

 this supposedly continuous system, Marshall has extended the use 

 of the term Oamaru System. This name had formerly been used 

 by Hutton to denote a portion only of the rocks thus designated 

 by Marshall. Hutton (1885, 1900) held that there was an 

 Upper Cretaceous Waipara System, followed unconformably by 

 the Oligocene Oamaru System, and this by the Miocene Pareora 

 System, which again is followed by the Pliooene Wanganui series 



